The order of precedence for pattern matching is as follows:

{}

:

whitespace . ..

?


The alternative operator has the lowest precedence. For example, suppose there are four patterns: A, B, C, and D.
A BC D
is equivalent to
{A B}{C D}
The example matches an input of A followed by B, or it matches an input of C followed by D.
Grouping patterns by using the braces has the highest level of precedence. For the patterns A, B, C, and D:
{AB} C D
is not equivalent to
AB C D